Creating an image with PHP code.

[feldmanjared]

Hello,

 

I have a website called http://flappycreator.com/ where users can upload multiple images to create their own version of Flappy Bird.  As a result of this I created a PHP page that takes a GET param to create a preview image of their game to display in various locations on the website.

 

Here is an example:

http://flappycreator.com/preview.php?id=5305a9ad9dc30

http://flappycreator.com/flappy.php?id=5305a9ad9dc30

http://flappycreator.com/share.php?id=5305a9ad9dc30

 

My issue is, I have given my users the ability to upload PNGs or JPGs and trying to figure out reliable code to display the preview has become a huge hassle.  In the example above the Pac-Man character shows a white background but when you play the game, it is actually transparent.  In other situations I am getting extremely bad color distortion.  The code I have provided is my final attempt after a ton of trial-and-error and the PNG imagealphablending() and imagesavealpha() commands have shown me the best results, however I don't know what they do.

 

Please help!  Thanks.

<?php

$bird_picture = "default/bird.png";
$tube1_picture = "default/tube1.png";
$tube2_picture = "default/tube2.png";
$ground_picture = "default/ground.png";
$bg_picture = "default/bg.png";

// If an id is set, then reset values
if (isset ( $_GET ['id'] )) {

	require ('XXX.php');
	$db = new DBAccess ();

	$query = "SELECT * FROM XXX WHERE XXX = '{$_GET['id']}'";
	$result = $db->query ( $query );
	$num_results = $result->num_rows;
	$row = mysqli_fetch_array ( $result );

	if ($num_results != 0) {
		if ($row ['bird_picture'] != "") {
			$bird_picture = "instances/" . $row ['folder_dir'] . "/" . $row ['bird_picture'];
		}

		if ($row ['tube1_picture'] != "") {
			$tube1_picture = "instances/" .$row ['folder_dir'] . "/" . $row ['tube1_picture'];
		}

		if ($row ['tube2_picture'] != "") {
			$tube2_picture = "instances/" .$row ['folder_dir'] . "/" . $row ['tube2_picture'];
		}

		if ($row ['ground_picture'] != "") {
			$ground_picture = "instances/" . $row ['folder_dir'] . "/" . $row ['ground_picture'];
		}

		if ($row ['bg_picture'] != "") {
			$bg_picture = "instances/" . $row ['folder_dir'] . "/" . $row ['bg_picture'];
		}
	}
}

$temp = explode(".", $bg_picture);
$extension = end($temp);
if ($extension == "jpeg" || $extension == "jpg") {
	$background = imagecreatefromjpeg($bg_picture);
} else {
	$background = imagecreatefrompng($bg_picture);
	// Turn off alpha blending and set alpha flag
	imagealphablending($background, true);
	imagesavealpha($background, true);
}

$temp = explode(".", $ground_picture);
$extension = end($temp);
if ($extension == "jpeg" || $extension == "jpg") {
	$ground = imagecreatefromjpeg($ground_picture);
} else {
	$ground = imagecreatefrompng($ground_picture);
	// Turn off alpha blending and set alpha flag
	imagealphablending($ground, false);
	imagesavealpha($ground, true);
}

$temp = explode(".", $bird_picture);
$extension = end($temp);
if ($extension == "jpeg" || $extension == "jpg") {
	$bird = imagecreatefromjpeg($bird_picture);
} else {
	$bird = imagecreatefrompng($bird_picture);
	// Turn off alpha blending and set alpha flag
	imagealphablending($bird, false);
	imagesavealpha($bird, true);
}

$temp = explode(".", $tube1_picture);
$extension = end($temp);
if ($extension == "jpeg" || $extension == "jpg") {
	$tube1 = imagecreatefromjpeg($tube1_picture);
} else {
	$tube1 = imagecreatefrompng($tube1_picture);
	// Turn off alpha blending and set alpha flag
	imagealphablending($tube1, false);
	imagesavealpha($tube1, true);
	
}

$temp = explode(".", $tube2_picture);
$extension = end($temp);
if ($extension == "jpeg" || $extension == "jpg") {
	$tube2 = imagecreatefromjpeg($tube2_picture);
} else {
	$tube2 = imagecreatefrompng($tube2_picture);
	// Turn off alpha blending and set alpha flag
	imagealphablending($tube2, false);
	imagesavealpha($tube2, true);
}

imagecopymerge($background, $tube1, 200, -200, 0, 0, 52, 320, 100);
imagecopymerge($background, $tube2, 200, 200, 0, 0, 52, 320, 100);
imagecopymerge($background, $ground, 0, 320, 0, 0, 336, 112, 100);
imagecopymerge($background, $bird, 70, 190, 0, 0, 36, 26, 100);


header('Content-Type: image/png');
imagepng($background);

# Destroy
imagedestroy($background);
imagedestroy($ground);
imagedestroy($bird);
imagedestroy($tube1);
imagedestroy($tube2);

?>

preview.php